Air conditioning system



Nov. 9, 1943. L. B. MILLER ETAL 2,333,729

AIR CONDITIONING SYSTEM Original Filed Julyl6, 1937 3 Sheets-Sheet J.

CIIIIIIII.

. 140.0 13. Millar' 7" I William. L.M Gra.'ih

John. E.1-[a.-ins

Nov. 9, 1943.

|.. B. MILLER ETAL 2,333,729

AIR CONDITIONING SYSTEM Original Filed Ju1y 16, 1937 5 Sheets-Sheet 2 EEQUENCE. CONTROL-5 T0 STA RT\NC1 AND \GNITION CONTROL-5 AND CONTROL-5 Invanta rs Lao B. Mina-1* William. LJ'IGMAIL.

John. E. Hiainas iommeg" Nov. 9, 1943. I L. B. MILLER ET AL 2,333,729

' AIR CONDITIONING SYSTEM Original Filed July 16, 1937 3 Sheets-Sheet 3 SPACE HUMIDITY Invmfi'ors 11cc B. NI-111cm William 11.14 Gram...

- v duh-n. E.1-Ea.i.ns

' Patented Nov. 9, 1943' AIR CONDITIONING srs'rEM Leo B. Miller, Milwaukee, Wis., William L. Mc-

Grath, Philadelphia, l'a., and John E. Haines, Minneapolis, Minn, assignors 'to Minneapolis- Honeywell Regulator Company, Minneapolis,

Minn, a corporation of Delaware Original application July 16, 1937, Serial lVo.

154,025. Divided and this application September 2. 1941, Serial No. 409,226

9 Claims.

This invention relates to air conditioning systems and is more particularly concerned with air conditioning systems for summer cooling of maintain proper temperature condition within a space, such sysstem being driven by an internal combustion engine and being provided with a re- I heater for reheating the'air after being cooled and dehumidified, such reheater being supplied with waste heat from the engine.

. More specifically, it is an object or our invention to provide a system of the type mentioned, with an automatic control system for varying the output of the engine and the operation of thereheater in accordance with changes in temperature and humidity conditions in a manner to maintain proper psychrometric conditions within the conditioned space.

A further object of our invention is the provision of a novel reheater arrangement for an air conditioningsystem having an internal combustion engine driven compressor, the heating medium for the reheater being heated by being passed in heat exchange relationship with a heat exchange fluid which is circulated to absorb heat from the en- 'gine cylinders and the exhaust gases. A still further object is to provide'an arrangement for storing the waste heat ejected by the engine as by storing a body of heated fluid which is heated with such waste heat, this stored heat being available for satsfying'various-demand forv heat such as for supplying domestic hot water and for reheat. More-specifically, it is an. object of our invention to automatically utilize the stored heating fluid for reheat as by passing said fluid through the reheater when reheat is required.

Another object of our invention is toprovide 'a control arrangement for an internal combustion driven air conditioning system which acts automatically to control the relative humidity within the conditioned space by varying the output of the internal combustion engine in accordance with changes in relative humidity, such system' also acting automatically to start and stop the engine. ,v

- Another object of our invention is the provision I ot'an air conditioning system having a cooling and dehumidifying device of th type having a damper controlled by -pass therearound and a reheater, the by-pass and reheater being sequential- 1y controlled in such manner that the reheater is not placed into operation until the by-pass damper is wide open, thereby avoiding addition of heat to they air being conditioned at all times except when such addition of heat is necessary in order to secure the required amount of dehumidification.

Another object is the provision of an air conditioning system having a refrigeration system for cooling and dehumidifying and having also a reheating means, such system being provided with a control arrangement for automatically controlling the operation of the refrigeration system and the reheater, such control arrangement acting to Other objects will become apparent from the following description and the appended claims.

For a full disclosure of our invention, reference is made to the following detailed description and to the accompanying drawings,- in which Figure 1 illustrates diagrammatically an air conditioning system embodying one form of our invention, v Figure 1A shows the same system as Figure l, but omits the'wirin'g diagram,

Figure 2 illustrates diagrammatically another form which'our invention may take, and

Figure 2A is a simplified showing of Figure 2, omitting the wiring diagram.

Referring now to Figure 1, reference character l indicates anair conditioning chamber having a return air inlet duct 2 whichleads from a space to be conditioned 3. Conditioning chamher ,I is also provided with a fresh air inlet duct 4, this duct being provided with suitable dampers 5 for controlling the admittance of fresh air. To the discharge end of conditioning chamber l is connected 9. fan 8, the discharge of this 19.1 being connected to a discharge duct 1 which leads to the conditioned space 3. The fan is provided' with suitable driving means such as an electric motor 8. Located within the conditioning chamher I is a cooling coil 9, a battle In being provided sage ll, face dampers l2 and lay-pass dampers flow of a combustible mixture of l3 are provided, these dampers being actuated by a rod 14 which is connected to the actuating arm of proportioning motor l5, the arrangement being such that when the face dampers are moved towards closed position the by-pass dampers are simultaneously moved towards open position and vice versa. The face dampers 12 it will be understood, are never entirely closed by motor l5 and permit air to flow across coil 9 at all times. Also located in the conditioning chamber l is a reheater 16.

For supplying liquid refrigerant to the cooling coil 9 and for withdrawing therefrom, a compression type of condensing unit is provided which comprises a compressor 11 and a condenser 18. The discharge of the compressor I1 is connected by means of conduit 15 to the refrigerant inlet of condenser l8. To the refrigerant outlet of the condenser is connected a conduit which may lead through a suitable receiver (not shown), to the inlet of an expansion valve 2|. This expansion valve may be of any desired type and is herein illustrated as being of the thermostatic type comprising a temperature control bulb connected to the outlet of the cooling coil 9. Said cooling coil outlet is connected by a conduit 22 to the suction side of the compressor 11. Compression refrigeration systems of this type are well known in the art and hence a detailed description of the operation of such a system is unnecessary here. However, it may be stated that operation of the compressor I1 causes chilling of the cooling coil 9, and that the amount of cooling done by cooling coil 9 varies with the compressor speed.

For driving the compressor l1 an internal combustion engine 25 is provided, this engine hav- I ing the usual inlet manifold 26, exhaust manifold 21, starting motor 28, generator 29, and a fly-wheel which has located therein a suitable clutching mechanism. In starting anengine of this type it is desirable to disconnect it from its load and for this purpose an'automatic clutching mechanism is provided which comprises a bell crank lever 3| for actuating the clutch release collar 32, the bell crank lever being-"connected to a, pneumatic motor 33. The pneumatic motor 33 comprises a piston 34 located in a suitable cylinder, this piston being urged outwardly by a spring 35, this causing disengagement of the clutching mechanism. The interior of the cylinderis connected by a conduit 35 to the intake manifold 26. By this arrangement, when the engine 25 is started the resulting vacuum in the intake manifold will cause movement of the piston 34 against the action of the spring 35 to engage the clutching mechanism, thus causing the engine 25 to rotate the drive shaft 31. The drive shaft 31 carries a pulley 38 which drives the belts 39 which in turn rotate the pulley 40 mounted on the compressor shaft, and in this manner the compressor 11 is driven by the internal combustion engine 25. Also mounted upon the shaft 31 is a second pulley 4|, this pulley being provided for driving the pumps 42 and 43 through the medium of belts 44.

For controlling the speed of the engine 25 a throttle valve 45 is provided which controls the fuel and air into the engine cylinders. It will be understood that a suitable fuel mixing device (not shown) is employed for mixing the fuel and air prior to passage to the throttle valve 45. The throttle valve 45. is controlled by means of a proportioning motor generally indicated at 46, thlsmotor evaporated refrigerant an operating shaft 41 upon which is actuating lever 48 which is connected to the throttle valve by suitable linkage. The operating shaft 41 is rotated through a gear train 49 by means of a pair of induction motors comprising armatures 50 and 5| and cooperating field coils 52 and 53. It will be understood that energization of the field coil 52 will cause rotation of the shaft 41 in one direction and energiz'ation of the fleldecoil 53 will cause rotation of said shaft in the opposite direction, the shaft 41 remaining stationary when both field coils are deene'rgized. No novelty is claimed for the proportioning motor illustrated herein, this type of proportioning motor being shown in the patent to D. G. Taylor, No. 2,028,110, and being controlled by a relay of the electrically balancing type. Mounted on the shaft 41 is an arm 55 which cooperates with a resistance 55 to form a balancing potentiometer. Also mounted on the shaft 41 is an insulated actuating member 51 for actuating the limit switches 58 and 59, these limit switches being provided for deenergizing the field coils 52 and 53 when the shaft 41 is rotated to one limit or the other of its travel.

For controlling the energization of the field coils 52 and 53, a balancing type of relay is provided, this relay being generally indicated as and comprises a pair of connected relay cells 6! and 52 for controlling through a suitable armature, a switch arm 53 which cooperates with a pair of contacts 64 and 65. When the relay coils GI and 52 are equally energized, the armature will assume a midposition in which the switch arm 63 is disengaged from both contact 64 and contact 65. If, however, the relay coil 62 is energized more highly than relay coil 61 the switch arm 63 will be brought into engagement with the contact 65. Conversely, if relay coil BI is energized more highly than relay coil 62 the switch arm 63 will be caused to engage the contact 64.

In accordance with our invention the speed of the engine is controlled in accordance with the relative humidity of the space being conditioned, and for this purpose thehumidity controller 66 is provided for controlling tions of'the relay coils BI and 62. The humidity controller 66 comprises a humidity responsive device 51 for controlling a potentiometer 68, this potentiometer comprising a slider 59 cooperating with a resistance coil 10. The humidity responsive device comprises upper and lower clamping members for securing a plurality of hairs or other moisture responsive strands, the lower clamping member being connected to a suitable fixed support and the upper clamping member being connected so as to actuate the slider 89. A spring II is provided for urging'movement of the slider 69 against the action of the humidity responsive device. Upon an increase in humidity the strands of the moisture responsive device 61 will increase in length, this permitting rotation of the slider 59 in a counter-clockwise direction under the action of spring 1|. A decrease in humidity, however, will. cause the moisture responsive strands to decrease in length, this causing rotation of slider 59 in a clockwise direction against the action of spring 1|. V

For supplementing the control of the ba ancing relay 60 by the humidity controller 55, :1 temperature controller 15 is provided, this temperature controller comprising a bellows 18 which is secured to a fixed support at its lower end and which is arranged to operate a pivoted mercury comprising mounted an the relative energizaswitch carrier 11 which carries a mercury switch lows 16 will contract, causing rotation of the i switch carrier 11 and mercury switch I8 in the opposite direction. This instrument may be so designed and adjusted that when the temperature of the return air isbelow 82 F., the bellows 16 will be contracted sufiiciently to cause the switch 78 to be tilted so that its right-hand contacts are closed. When, however, the temperature of the return air exceeds 82 F., the bellows 16 will expand to cause breaking of the right-hand contacts of mercury switch 18 and making of the left-hand contacts thereof.

Reference character 8| indicates a step-downtransformer connected to any suitable source of power, the secondary 82 of said transformer being connected across the serially connected relay coils 6| and 62 by means of wires 83, 84, 65 and 66. Also connected across theserlally connected relay coils 6| and 62 are the resistance 56 of the balancing potentiometer and the control resistance of the humidity controller, the resistance 56 being connected to said relay coils by means of wires 81 and 88 and the protective resistances 89 and 99. The control resistance 19 is connected to said relay coils by wires 9| and 92 through the protective resistances 89 and 90. The slider 55 of the balancing potentiometer is connected to the junction of the relaycoils 6| and 62 by means of wires 93 and 94. The junction of relay coils 6| and 62 is also connected to the common terminals of the mercury switch 18 by means of wires 94 and 95. terminal of mercury switch 18 is connected by a wire 96 t0 the slider 69 of the humidity controller. It should thus be seen that when the mercury switch 18 is tilted to the position shown,

the slider 69 of the' humidity controller is connected to the junction of relay coils 6| and '62.

The right-hand The left-hand contact of the mercury switch 18.

is connected by means of wire 91' to the left-hand end of the control resistance 10.

From the foregoing wiring connections, it will be apparent that the slider 69 of the'humidity controller 66 will place the portion of the control resistance 19 which lies to the left of said slider in parallel with the relay coil 62, and will place the portion of. resistance 18 lying to the right of the sliderin parallel with the relay coil 6 I. Thus as the slider 69 moves across the control resistance to the left due to an increase in relative humidity, the portion of the resistance 10 which is in parallel withthe relay coil 62 will be decreased and field coil 53, wire um and wire as to the other side of secondary 92. This willresult in rotation of the shaft 41 in a direction to cause opening of the throttle valve 45 and to cause counter-clockwis rotation of the slider 01' the balancing potentiometer.

This movement of the slider 55.

will have the effect of decreasing the portion of balancing resistance 56 which is in, parallel with the relay coil 6| and increasing the portion of ,said resistance which is in parallel with the relay coil 62. This action therefore tends to balance out the initial unbalancing efiect on the relay 68 caused by the humidity controller 66. When the movement -of slider 55 is such that its balancing action balances out the initial unbalancing action of the humidity controller, the relay coils 6|- and 62 will become equally energized thereby causing the switch arm 63 to disengage contact 64, thus stopping the motor in this new position. It should thus be seen that the angular travel of the shaft 41 will be proportional to the travel of the slider 69 of the humidity con- 'troller across the control resistance Hi. It should be apparent that upon decrease in relative humidity the slider 69 will travel in the opposite direction across the control resistance I0, this un-' balancing the relay in the opposite direction, thuscausing the switch arm 63 to engage the contact 65 for energizing the field coil 52 which will result in the shaft 41 being rotated in a direction to close the throttle valve 45. It should also be apparent that this rotation of the shaft humidity increases, and being closed to decreasev thespeed of the engine as the humidity decreases.

With the parts in the position shown,'it will be noted that the slider 69 of the humidity controller is engaging the extreme right-hand end of the control resistance 19 thus indicating that thehumidity of the air within the conditioned space is very low. For this condition it will be noted the proportioning motor has assumed a position in which the throttle valve 45 is. completely closed,

' the limit switch 58 at this time being opened to deenergize the motor field 52. If should at any time the temperature of the air within the conditioned space exceed 82 F., the temperature controller 15 will cause the mercury switch 19 to be tilted in a counter-clockwise direction to break the right-hand contacts andto make the left-hand contacts. The breaking of the righthand contacts will disconnect the slider 69 from theiunction of the relay coils 6| and 62 and thus flthe position of the slider 69 on the resistance 19 the portion'of'said resistance which is in parallel with the relay coil 6| will be increased. This will result in an increase in current flow through the relay coil 6| and a decrease in current flow through the relay coil 62 which causes, engagement of switch arm 63 with contact 64. Engagement of switch arm 63 with contact 64 will energize the field coil 53 by a circuit as follows:

will no longer have any effect upon the energization of said relay coils. The making of the left-hand contacts of mercury switch 18 will cause the relay coil 62 to be substantially short-circuited-by the following circuit: left-hand end of relay coil 62, wire 94, wire95, mercury switch 18, wire 91, wire 92, and protective resistance 99 to the right-hand end of relay coil 62. This will highly energized than relay coil 62 thus causing switch arm 63 to engage the contact 64 which cause the relay coil 6| to be considerably more capable of rebalancing the relay 80 andtherefore the throttle valve 45 will be moved to wideopen position for causing the engine to operate at maximum speed for reducing the excessive temperature.

From the foregoing description, it should be apparent that so long as the space temperature is below a predetermined value, the compressor speed and hence the coil temperature will be controlled in accordance with the relative humidity conditions within the conditioned space. Thus as the relative humidity increases, the compressor speed will be increased, this resulting in a lowering of coil temperature. This lowering in the cooling coil temperature will result in an increase of the dehumidifying action of said coil. Similarly, upon falling relative humidity the cornpressor speed will be reduced, this causing the cooling coil temperature to increase thereby decreasing the dehumidifying action of said cooling coil. By controlling the compressor speed in accordance with the relative humidity within the conditioned space, this condition is maintained within predetermined limits. If at any time the temperature within the conditioned space becomes excessive, it will be apparent that the temperature controller I will cause operation of the compressor at maximum output for reducing such excessive temperature condition.

Our invention also contemplates the provision of automatic stopping and starting mechanism for the internal combustion engine 25. This mechanism will now be described. Actuated by the proportioning motor shaft 41 is a switching member IOI which is arranged to actuate the auxiliary switch formed of mercury switch I02 which is mounted upon carrier I03. -The switching member IN is so adjusted upon the shaft 41 that when the throttle valve is closed to such a point as to indicate the minimum desired operation of the engine 25, said switching member willcause tilting of mercury switch I02 to open position. When, however, the throttle valve is opened sufliciently to cause efllcient and satisfactory operation of the engine 25, the switching member IOI will permit tilting of switch I02 to closed position under the action of tension spring I03a.

Reference character I04 indicates a storage battery, one terminal of which is connected by means of wire I05 to the mercury switch I02, and the other terminal of which is connected by wire I06 to a suitable ground connection. The

other terminal of mercury switch I02 is connected by wires I01 and I08 to one terminal of an ignition coil I09 for the engine 25, the other terminal of said ignition coil being grounded. By the arrangement just described, the ignition coil I00 will be energized whenever the throttle valve 45 is opened sufllciently to permit closing of the mercury switch I02. The mercury switch I02 is also connected by wire 0- to the starting motor relay III. Thus simultaneously with the energizing of the ignition coil I08 the starting motor relay will be caused to energize the starting motor 28 for cranking the engine. This starting motor relay is arranged to automatically cause deenergization of the starting motor 28 when the engine starts, and is also arranged to prevent energization of said starting motor so long as the engine is in operation. For the constructural details of the starting motor relay III and the principles of operation thereof, reference is made to Patent No. 1,773,913, issued on August 26, 1930, to L. K. Loehr et al. Reference character II2 indicates an automatic cutout for the. generator 20 which disconnects said generator from the storage battery whenever the engine is out of operation.

From the foregoing it should be seen that when the throttle valve is automatically'opened to such an extent as to permit satisfactory operation of the engine, the engine will be automatically started by the closing of mercury switch I02. It should also be apparent that when the throttle valve 45 is closed to such an extent that the engine no longer operates satisfactorily and efficiently, the switching member IOI will cause opening of mercury switch I02 which will deenergize the ignition coil I00 for the engine, thus placing said' engine out of operation.

Our invention contemplates not only controlling the compressor speed in accordance with relative humidity, but also contemplates control of the temperature of the conditioned space by controlling the amount of air passed over the cooling coil 9, and also by reheating the air when necessary. Our invention further contemplates the recovering of the waste heat given off by theinternal combustion engine and the condenser, and the utilizing of this waste heat for reheating when necessary, and also for other uses such as providing a supply of domestic water. This heat recovery system will now be described. Reference character II5 indicates a suitable form of cooler which may take the form of an evaporative cooler or a spray pond. Connected to the cooler H5 is a conduit IIO for withdrawing cold water from said cooler, this conduit being connected to the intake of circulating pump 43, the discharge of said pump being connected by a. conduit II! to the cooling water inlet of the condenser I8. The cooling water outlet of the condenser I8 is connected by a conduit II8 to the inlet of the cooling water jacket of the engine 25, the outlet of said jacket being connected by a conduit IIO to the coil I20 located within the exhaust gas heat exchanger I2I. This heat exchanger is connected by pipe I22 to the exhaust manifold 21 and hence the exhaust gases for the engine pass in contact with the coil I20 located within the heat exchanger. The outlet of the heat exchanger IZI is connected by a conduit I23 to the inlet of coil I24 which is located within a storage tank I25. The outlet of the heat exchange coil I24 is connected by a conduit I26 to the inlet of the cooler I I5.

From the foregoing it should be seen that cold water is first passed through the condenser for cooling the condenser to effect liquification of the gaseous refrigerant, this cooling water therebgbecoming heated by the heat withdrawn from the refrigerant. This heated. water then passes into the water Jacket of the engine whic is con- .siderablywarmer than the condensen and is form a control potentiometer.

The water or other fluid in the storage tank I24. may obviously be used for-any desired purpose, such as providing a supply of domestic hot water. This heated fluid is also adaptablefor providing a supply of heat to the reheater I and for this purpose the reheater I0 is connected to' .the outlet of the storage tank I25 by means of conduit I21. The outlet of the reheater I0 is connected by a conduit I28 to the intake of the circulating pump 42, the discharge of this pump being connected by' conduit I29 to the inlet of the storage tank I25, a throttling valve I30 being interposed in said conduit.

In accordance with one form of our invention, .we provide a temperature controlled system for maintaining the temperature within the conditioned space within predetermined limits, this being accomplished by controlling the flow of air over the cooling coil, and also by providing reheat. In accordance with our invention, upon falling temperature we first gradually reduce the air flow across the cooling coil 9 and increase the air flow through the by-pass, and if the temperature still continues to fall after the by-pass is wide open the reheater is-placed into operation.

} The control mechanism for'achieving this result will now be described.

Reference character-I35 indicates generally a temperature controller, this temperature con-.

lows I30 is arranged to cooperate with a bell crank lever I39 having an actuating arm I40 and a control arm I4I, said control arm I being arranged to'contact a,control resistance I42 to A spring I43 is connected to the actuating arm I40 and urges this arm downwardly against the bellows I30. The bellows I30, tube I31, and bulb I30 are filled with a suitable volatile fluid wherefore the pressures within bellows I30 will vary with the temperature to which the control bulb I 30 is subjected.' When the return air temperature increases, the pressure of the volatile fluid will increase, this causing expansion of the bellows I30 and movement of the control arm I to the left across resistance I42 against the action of spring I43. Upon falling return air temperature, the pressure of the volatile fill decreases; this permitting the spring I43 to'cause travel of control arm I4I across the control resistance I42 in the opposite direction.

The return air controller I35 is connected to the proportioning motor I44, this motor being of the type shown and described in the Taylor Patent 2,028,110. As should now be apparent, the shaft I45 of the proportioning motor I44 will ass'ume angular positions corresponding to the position of the control arm I4I 'on the control re' sistance I42. In other words, for each value of return air temperature the operating shaft I 45' operates the reheat control .valve I 30. It willbe noted that the control resistances I 40 and I49 are arranged'so as to occupy but a portion of the range of rotation of their respective sliders, the resistance I40 being arranged to the left of the center of movement of the sliders I40 and I",

5 and the resistance I49 being arranged to the right of such center of rotation. By this arrangement, it will be seen that as the shaft I45 rotates from its extreme counter-clockwise limit of rotation, the slider I40 will travel across the resistance I40 while the slider I41 engages contact segment I49a which is attached to the extreme left-hand end of resistance I49. Upon continued clockwise rotation of the shaft I45,-the slider I40 will ride off the resistance I40 onto contact segment Ba, and the slider I41 will ride from the contact segment I49a onto-the control resistance I49.

The proportioning motor I5 is connected to the resistance I43 and the slider I40 in such manner that upon clockwise rotation of the slider I40, the by-pass damper I3 is opened and the face damper I2 is closed. The proportioning motor I50 which controls the valve I30 is connected to the re-- sistance I49 and the slider I41 in such manner that as the slider I41 is rotated in a clockwise direction the valve I is gradually opened. With the operating shaft I45 in the position shown, the slider I40 is engaging the midportion of the resistance I48 and consequently the'proportioning motor I5 has assumed a positionin which the 30 face and by-pass dampers are in midposition.

Also the slider I41 is contacting the contact segment I49a and therefore the proportioning motor I50 has assumed the position in which the reheat valve I30 is closed. If now should the return air temperaturev decrease, the temperature controller I35 will cause the roportioning motor I44 to rotate the shaft I45 in a clockwise direction, this causing movement of the slider I across the resistance I48 to the right, thereby 40 causing the proportioning motor I5 to open further the by-pass damper I3 and to close further the face damper I2. At this time, the valve I30 will remain closed due to the slider I41 not having yet engaged the end of control resistance I49.

Upon a further fall in temperature, th by-pass dampers I3 will be further opened. and the face dampers I2 will be'further closed, and when the fall in temperature is such that the slider I40 engages the extreme right-hand end of the resistance I40, the by-pass dampers I3 will be completely opened. f Upon continued fall in temperature the slider I40 will begin sliding across the resistance I49, this causing the proportioningmotor I to open gradually the valve I30. By this arrangement it should be apparent that so long as the space temperature is above a predetermined value the reheater valve I30 will remain closed and the control ofthe temperature willbe effected solely by adjusting the face and bypass dampers. When, however, the by-pass dampers aremoved to completely open position and the temperature continues to fall, the reheater control valve I30 will begin opening, thereby providing a supply of heated fluid to the reheater, the quantity of heated fluid supplied being progressively increased as the temperature continues to fall.

' From the foregoing description it shouldbe apparent that our invention provides automatic 'cgntrolof the internal combustion engine in ac- -cordance with the relative humidity of the space ,to beconditioned, this system acting automati- Jcally to start the engine whenever the relative humidity rises to such a value that the cooling load would be sufiiclent to require the engine to 70 operate at a satisfactory operatingspeed. It

crease in air flow will result should further be apparent that as the relative humidity increases, the speed of the engine will be increased, this causing the temperature of the cooling coil to be decreased thereby increasing the dehumidifying effect of the coil to prevent further increase in such relative humidity. Upon a decrease in relative humidity, the speed of the engine will be decreased, thus decreasing the temperature of the cooling coil and thereby decreasing the dehumidifying action. The compressor speed is therefore controlled in a manner to maintain proper relative humidity conditions within the space so long as the temperature within the space is not excessive.

Simultaneously with the control of the cooling coil temperature by the relative humidity conditlons, the fiow of air over the cooling coil is controlled in order to maintain the temperature conditions within the space at the desired value. Thus as the temperature within the space increases, the air flow across the cooling coil is increased to increase the cooling action of said cooling coil. It will be apparent that this inin increasing the temperature of the cooling coil, thereby decreasing the dehumidifying efiect of such coil. This will result in the relative humidity within the space eventually increasing and the humidity controller 66 in response will cause the speed of the engine to be increased to carry this increase in cooling load due to the temperature in-' crease within the space. It should also be apparent that upon a decrease in temperature withinthe space. the temperature controller I35 will act to cause closing of the face dampers l2 and opening of the by-pass dampers [3, this decreasing the flow of air across the cooling coil 9 thereby decreasing the cooling effect of said coil upon the air, thus tending to prevent further fall in space temperature.

In the event that the cooling load is light but the relative humidity within the space is excessive, the cooling coil may be lowered in temperature for dehumidiflcation purposes, to such an extent that the space is overcooled even though the by-pass dampers l3 are wide open. If such a'condition should occur, the temperature controller I35 will cause opening of the reheat control valve I30 thus providing a supply of heat for r heating the air after it has been cooled for dehumidifying purposes. By the sequential control of the face and by-pass dampers and of the reheater, reheat is first provided by by-passing air around the cooling coil and when such arrangement is incapable of from falling, the reheater is placed into operation. This sequential control thus provides reheat without actually adding heat to the air being conditioned so long as possible, and adds heat to the air being conditioned only when the operation of the system for dehumidiflcation results in cooling of the air to such an extent that reheat is required. Then and only then is reheat supplied.

From the foregoing description, it should also be apparent that whenever the temperature within the conditioned space becomes excessive, the control of the speed of the internal combustion engine is taken away from the humidity controller and the engine is operated even though the humidity may be relatively low. The system which we have disclosed, therefore, provides a very flexible and simple arrangement for maintaining proper conditions within the conditioned space regardless of the type of conditioning load.

preventing the temperature Figure 2 Referring now to-Fig. 2, we have shown in this figure a modified form of control system. The internal combustion engine controls,- the refrigeration system and the conditioning chamber are substantially the same as in Fig. l and are indicated by the same reference characters. In this embodiment, however, the compressor speed is not varied in accordance with changes in relative humidity as in Fig. l, but is varied in a manner to maintain the air leaving the cooling coil at a constant dew-point temperature. For this purpose the compressor is controlled in accordance with the suction pressure of the refrigeration system by means of the suction pressure controller 200, this controller being arranged to control the proportioning motor 46 which in turn adjusts the throttle valve 45. Also, in Fig. 2, instead of controlling the dampers I2 and. iii in accordance with return air temperature alone, the

control of said dampers is effected in accordance with the effective temperature within the conditioned space, the value of effective temperature 7 being raised or lowered in accordance with variations in outside temperature.

Due to the use of dew-point control, it is desirable to pass air over the cooling coil at all times. For this purpose, the face dampers l2 may be arranged so that they do not completely close, thereby insuring that at least a predetermined amount of air will flow across said coil at all times.

Referring 'now to the suction pressure controller 200, this controller comprises a bellows 20!, the interior of which is connected to the suction line 22 of the refrigeration system by means of a conduit 202. The bellows 20l is arranged to actuate a bell-crank lever comprising an actuating arm 203 and a control arm 204, said control arm cooperating with a control resistance 205 to form a control potentiometer for controlling the proportioning motor 46. The actuating arm 203 is connected to a spring 206 which urges said arm downwardly against the bellows 20L Upon an increase in suction pressure the bellows 20| will expand, this causing counter-clockwise rotation of actuating arm 203 and movement of control arm 204 to toe left across control resistance 205,

this causing the proportioning motor 46 to rotate its operating arm in a direction to open-further the throttle valve 45. Upon a decrease in suction pressure the bellows 20l will be contracted by the action of spring 203, this causing travel of the control arm 204 to the right across resistance 205, which in turn results in movement of the proportioning motor 46 in a direction to move the throttle valve towards closed position. The suction pressure controller 200 therefore acts to increase the speed of the engine upon an increase in suction pressure and to decrease the speed of the engine upon a decrease in suction pressure in a manner to maintain the suction pressure within predetermined limits.

The proportioning motor [5 which actuates the face and by-pass dampers l2 and'l3 comprises an operating shaft 208 upon which is mounted a lever 209 which in turn is connected to the operating member l4 for the dampers. The operating shaft 208 is rotated through a gear train 2l0 by means of a pair of induction motors comprising armatures 2| Land H2 and corresponding field coils H3 and 214. It will be understood that the motor formed of armature 2H and field coil 2l3 acts to. drive the operating shaft 208 in one direction and that the motor formed of armature 2l2 and field coil 2|4 acts to drive said oper-. ating shaft inthe opposite direction.

The energization of field coils 2| 3- and 2 is controlled by means of the balancing relay 2|5,

this relay comprising connected relay coils 2l6 and 2". The relay coils 2l6 and 2H control through a suitable armature a switch arm 216 which cooperates with a pair of contacts 2l9 and 229. It will be understood that when relay coil 2" is energized more highly than relay coil 216, the switch arm 218 will engage the contact 226. Conversely, when the relay coil M6 is energized more highly than relay coil 2" the switch arm 2l6will be caused to engage the contact 2I9.

For controlling the energization of the relay coils 2l6'and 2" are a return air temperature controller 221, a space relative humidity controller 222, an outside temperature compensator 22 3,

and the balancing potentiometer 224, this balancing potentiometer comprising a slider 225 mounted .upon the operating shaft 208 of the proporfore the pressures within the bellows vary in ac-.

cordance with the return air temperature. The bellows 221 is fixed at its lower end and is arranged to actuate alever 230'which in turn actuates a control arm 23l and a 'corrector arm. 232,

the control arm 23l engaging a control resistance I 233 and the corrector arm 232 engaging a correc-' the space temperature decreases, the bellows will contract under the action of the spring shown, this causing counter-clockwise rotation of the control arms 23! and 232 across their respective resistances,-and that upon an increase'in temperature, the bellows 221 will expand thus causing movement of said control arms in the opposite direction.

The humidity controller 222 comprises a humidity responsive device including a plurality of strands 235 of'hair or other-moisture responsive material, these strands being connected at their upper ends to a clamping member 236 and at their in accordance with outside temperature. Bellows 245 cooperates with'a bell crank lever having an actuating arm 246 and a control arm 249, said control arm cooperating with the control resistance 25!! to form a control potentiometer.

It will be apparent that upon an increase in outside temperature, the bellows 245 will expand against the. action of the spring shown, thus causing movement of the control arm 249 to the right across the control resistance 256. Conversely. upon a decrease in temperature the bellows 245 will contract and the control am 249 will be moved in the opposite direction underthe action of the spring.

' Reference character 25l indicates a step-down transformer having a high voltage primary 252 and alow voltagesecondary 253. The upper end of secondary 253 is connected to a wire 254, this wire in turn being connected to the left end. of resistance 2 by wire 255, to the left=end of resistance 233 by wire 256, to the left end of the balancing resistance 226 by the wire 251, and to the right-hand end of resistance 256 by wire 256.

To the lower end of. the transformer secondary- 253 is connected a wire 259, this wire being connected to the other ends of the four resistances just mentioned. The left-hand end of the relay coil 2l6 is connected to the wire 254 by means of wire 269 and is therefore connected to the up-' per end of the transformer secondary 253. The right-hand end of the relay coil 211 is connected by wire 26! to the wire 259 and is therefore connected to the lower end of the transformer secondary. From the foregoing wiring arrangement, it should be apparent that the three control resistances 233, 2 and 259, the balancing resistance 226, and the relay coils 2l6 and 2" in series, are connected in parallel across the termi- 'tor resistance 234. Itwill be understood that as lower ends to a clamping member 231, this clam p ing member being secured to a suitable stationaryelement. The upperclamping member 236, however, is connected to the actuating arm 236 of a bell crank lever including a control arm 239. A tension spring.;246 is also-connected towthe actuating arm 238 and serves to maintain the strands 235 taut. 'Upon a decrease in relative humidity, the strands 235 will decrease in length, this causing downward movement of the actuating arm 236 against the action of the spring nals of the secondary 253. A flow of current will "therefore take place through each of the resistances-andthrough the relay coils. To the junction of relay coils 2 l6 and 211 is connected a wire 262, this wire being connected to the control arms 2", 239, 249, and to the balancing arm 226' as shown, rheostats 263, 264 and 265 being interposed between this wire 262 and the control arms 239, 249, and the balancing arm 225 respectively.

By this arrangement it will be apparent that each Y of the control. arms. and the balancing arm divides its respective resistance into a first portion which is'in parallel with the relay coil 2l6 and a second portion which is in parallel with the relay coil 2". Movement of any one of the control arms or the balancing arm across its respective resistance will therefore vary the resistance in parallel with each of the relay coils, and thereby vary the relative energizationsvof said relay coils v 246 thus rotating the control arm 239 to the left 1 across its control resistance 241. Upon an in-- crease in humidity, however, the strands 235 will control arm will be rotated in the opposite direction under the action of the spring 246.

The outside temperature compensator 223 comprises a bellows 245 which is connected by a tube 246 to a control bulb 241 which may be located ln the fresh air duct. This bulb, tube and bellows are filled with a suitable volatile fluid wherefore the pressure within the bellows, 245 varies .increase in length and the actuating arm and each control arm is engaging the midportion of its corresponding resistance and the proportion- Withgthe controllers in-the position. shown,

ins motor l5 has therefore assumed an intermediate position in which the balancing'arm 225 engages the center of, the balancing resistance r 226', this resulting in the relay coils2l6 and 211 being equally energized, thereby causing the switch arm 2" to be disengaged from the contacts2l9 and 226. For this position ofthe motor the dampers l2 and I3 are each in half-open position. It now should the space temperature increase, the control arm 231 of the controller 22! will be shifted to the right, this decreasing the Portion of the control resistance 233 which is in parallel with the relay coil 2 and increasing the portion of said resistance which is in parallel wlth'the relay'coil 216. This will result in increase the portion a the by-pass dampers to potentiometer a decrease in current flow through the relay coil 2H and an increase in the current flow through relay coil 2i6, this causing the switch arm 2l8 to engagethe contact 2!!! and energize the motor field 213 by a circuit as follows: transformer secondary 253, wire 254, wire 266, motor field 213, wire 2G1, contact 219, switch arm 2l8, and wire 288 to the other side of secondary 253. This energization of the motor field 2|3 will cause the operating shaft of the motor to be rotated in a direction to open the face dampers l2 and to close the by-pass dampers i3. At the same time the balancing arm 225 will be shifted to the left across the balancing resistance 226. This will decrease the portion of said balancing resistance which is in parallel with the relay coil 2l6 and of said resistance which is in parallel with the relay coil 2H, this causing an increase i current flow in the relay coil 2i! and a decrease in current flow in relay coil 2H5, thereby tending to balance out the initial unbalancing effect of the controller 22!. When the shaft 208 has been rotated sufflciently to cause the balancing potentiometer to balance out the initial unbalancing action of the controller 22!,

the current flow in the relay coils 2H; and 211 will become equalized, this resulting in the switch arm 2l8 disengaging the contact 2l9 thereby stopping the motor in this new position. It will be apparent that the greater the initial unbalancing action is, the further the shaft 288 must rotate for causing the balancing potentiometer to balance out such unbalancing action. The

rotation of the shaft 208 will therefore be in proportion to the movement of the control arm having the effect tive to the control potentiometer of the controller 22l, a relatively small movement of the control arm 23i on its control resistance 233 may be made to create a unbalancing action on the relay 2l5 such that a relatively large movement of the balancing potentiometer is required for v rebalancing. Thus by properly adjusting the rheostat 285, the proportioning motor l5 may be made to shift the dampers from one extreme position to the other for a movement of the control arm 23! through but part of its operating range. In other words, the rheostat 285 acts to make the operating range of the controller 22i less than its total range.

If the humidity within the space should increase, the control arm 239 will be shifted to the right across the control resistance 2", this of decreasing the portion of said resistance which is in parallel with the relay coil 2H and increasing the portion of. said resistance which is in parallel with the relay coil '2i6, thus causing a decrease in current how in coil 2|! and an increase in current flow in coil 22l on its control resistance. The movements of the face and by-pass dampers will therefore be in proportion to the space temperature change. Upon a fall intemperature it will be apparent that the controller 22l will cause the relay coil 2|] to be more highly energized than the relay coil 2l6, this causing the switch arm 2l8 to engage the contact 220, this energizing the motor field 2 to rotate the shaft 208 in a direction to close the face dampers i2 and to open the by-pass dampers l3. As in the case of increasing temperature, the movement of the dampers l2 and I8 upon falling temperature will be in proportion to the change in temperature.

The control arrangement just described will act to maintain the the range of the controller '22I assuming of course that the capacity of the refrigeratio system is sufllcient for all conditions. Thus, if the cooling load should increase, the space temperature will increase and in response to such an increase in temperature the controller 22i will cause the face dampers to be opened further and be moved towards closed position. This will result i an increase in air flow across the cooling coil, thereby increasing the cooling etfect of the refrigeration system to 'offset the increase in refrigeration load.

It will be noted that the rheostat 265 is interposed between the balancing potentiometer and the junction of the relay coils 2 l8 and 2". The purpose of this rheostat is to desensitize the balancing potentiometer, thereby increasing the sensitivity of the controller 22!. In other words, the rheostat 2B5 acts to limit the flow of current through the balancing arm 225 of the balancing and thus decreases the effect of said balancing potentiometer .upon the relative energizations of relay coils H8 and 2H. By thus desensitizing the balancing potentiometer relaspace temperature within Hi, this causing the switch arm M8 to engage the contact 2l9, thereby energizing the motor field 2!! to cause rotation of the operating shaft 288 in the direction to open the face dampers l2 and to close the by-pass dampers l3. The resulting movement of the balancing potentiometer will tend to balance out the initial unbalancing effect created by the controller 222, and when the rotation of the shaft 208 is such that the balancing potentiometer completely balances out said unbalancing effect, the switch arm 2i8 will disengage contact 219, thereby stopping the motor and dampers in this new position. Upon a decrease in humidity it will be apparent that the opposite action will take place. In other words, the operating shaft of the motor will be rotated in the opposite direction an amount ,corresponding to the decrease in humidity. The humidity controller 222 will therefore act to cause the proportioning motor IE to position the dampers for increasing the air flow across the cooling coil 8 upon an increase in humidity and to cause opposite movement upon a decrease in humidity.

Assuming now that the space temperature remains constant but the relative humidity increases, the controller 222 in the manner just described will cause movement of the face damper l2 towards open position and the by-pass damper l8 towards closed position. This will result in an increase in cooling effect of the cooling coil 8 which ultimately will result in the space temperature beginning to fall. As the space temperature falls, the controller 22l will cause the proportioning motor l5 gradually to close the face dampers l2 and to open the by-pass dampers l8, thereby decreasing the cooling effectpr the system, and when the space temperature falls sufllciently that the decrease in cooling effect caused thereby is suflicient to prevent further fall in temperature,

midity. It will be observed that the rheostat 262 is connected between the control arm 239 of said humidity controller and the junction of the relay coils 2I6 and 2I1. The purpose of this rheostat is to vary the effect of the humidity controller upon the control point of the temperature controller. By properly adjusting this rheostat, the humidity controller may be made to vary the control point of the temperature controller upon a change in relative humidity an amount which just compensates for the change in effective or comfort temperature caused by such change in relative humidity. The temperature controller HI and the humidity controller 222 therefore cooperate to maintain a constant effective temperature within the space, the dry bulb temperature being raised or lowered upon changes in relative humidity to accomplish this result.

Assuming now that the space temperature and relative humidity remain constant, if the outside temperature should increase, the control arm 249 of the controller 223 will be shifted to the right across the control resistance 250, this acting to decrease the portion of said resistance which is in parallel with the relay coil 2 I 5, and to increase the portion of said resistance which is in parallel with the relay coil 2", this causing an increase in current flow in relay coil 2", and a decrease in current flow in relay coil 2 I3, which results in the switch arm 2 I8 engaging the contact 220 for rotation of the operating shaft 208 in a direction to close the face dampers I2 and to open the bypass dampers I3. Simultaneously the balancing am 225 of the balancing potentiometer will be shifted to the right across the resistance 223, this decreasing the portion of said resistance which is in parallel with relay coil 2" and increasing the portion of said resistance which is in parallel with relay coil 2 I6, thereby tending to balance out the initial unbalancing action of the controller 223. When the movement of the dampers and the balancing arm 225 is suflicient to cause rebalaneing of the relay, the switch arm 2| 8 will disengage contact 220 and the proportioning motor will stop in this new position. It should thus be apparent that upon an increase in outside temperature, the controller 223 will act to cause the air flow across the cooling coil 9 to be decreased and the air flow by-passed therearound to be increased. Upon a decrease in outside temperature the opposite action will take place, that is, the dampers will be moved so that the air flow across the cooling coil 9 is increased.

Assuming now that the outside temperature rises, the dampers I2 and I3 will be positioned in the manner just described to cause a decrease in flow of air across the cooling coil thereby decreasing the cooling effect of said coil. This decrease in cooling effect will eventually result in rising of temperature within the conditioned space, this rise in temperature acting upon the controller 22I in a manner to cause opening of the face dampers I2 and closing of the by-pass dampers I3 to increase gradually the cooling eflect. When the rise in space temperature is such that the resulting increase in cooling efiect caused by the controller 22I is sufficient to prevent further rise in temperature, the space temperature will be held constant at this new value. The outdoor temperature responsive controller therefore acts upon rising outdoor temperature to cause the return air temperature controller to maintain a higher value of temperature within the conditioned space. It will be apparent that upon falling outdoor temperature, the opposite action will take LAG place, namely, the controller 22I will be caused to maintain a lower value of temperature within the conditioned space. The purpose of this controller for the by-pass arrangement will usually provide suflicient reheat for the air discharged from the cooling coil. In certain installations, however, the continuous operation of the cooling coil for maintaining a constant dew-point of the discharged air may at times cause overcooling of the conditioned space, and a reheater maytherefore be desirable. If desired, the reheater if employed may be sequentially controlled with the face and by-pass dampers as in Fig. 1. In Fig. 2, however, instead of illustrating modulating control of the reheater as in Fig. 1, we have shown in this figure a two-position type of control. This reheat controller comprises a cam 210 mounted upon the operating shaft 208 of the proportioning motor I5, this cam cooperating with a pivoted switch carrier 2'" carrying a mercury switch 212. The cam 210 is arranged upon the proportioning motor shaft 208 in such manner that the switch is tilted to closed position only when the operating shaft is moved to its extreme limit of rotation, in which the face dampers I2 are moved to their minimum positions and the by-pass dampers I3 are opened. For other positions of the face and by-pass dampers, the cam 210 will cause tilting of the mercury switch 212 to open position. The pump in this instance, instead of being driven by the internal combustion engine is driven by an electric motor 213, the operation of this motor being controlled by the mercury switch 212. From this arrangement, it will be apparent that as the space temperature falls, the face dampers I2 will be closed gradually and the by-pass dampers I3 will be opened gradually. Upon continued fall in temperature, the face dampers I2 will eventually assume a maximum closed position and the by-pass dampers will assume a wide open position, at which time the cam 210 will be rotated just sumciently to cause making of mercury switch 212 which results in operation of the pump motor 213, causing a circulation of heated water from the storage tank I25 through the reheater I6 and back to the tank. When the pump is out of operation, circulation of water from the tank I25 through the reheater I6 is prevented by means such as a loaded check valve 214.

During the operation of the system just described, it will be apparent that the return air temperature controller 22I, the humidity controller 222, and the outside temperature controller 223 will act to position the face and bypass dampers in such manner that an effective temperature, as determined by the prevailing value of outside temperature, is maintained. Thus upon an increase in the effective temperature, the face dampers I2 will be moved towards open position and the by-pass dampers I3 will be moved towards closed position in a manner to increase the cooling effect of the system sufiiciently to prevent further increase in effective temperature. The resulting increase in air flow over the cooling coil 9 will increase the amount of refrigerant evaporated within said cooling coil, and hence will cause the suction pressure to increase. This increase in suction pressure will effect the suction pressure controller 200 in a manner to cause the proportioning motor 45 to open the throttle valve 45 farther. This will increase the flow of fuel to the internal combustion engine 25, thereby increasing its speed which in turn results in increased output of the compressor H. In this manner the compressor output will be increased upon an increase in effective temperature within the space. Upon falling effective temperature, it will be apparent that the opposite action will take place, namely, that the face and by-pass dampers will be positioned to restrict the flow of air across the cooling coil 9. This will result in less refrigerant being evaporated within said cooling coil, which in turn will cause lowering of the suction pressure. In response to this decrease in suction pressure, the pressure controller 200 will cause operation of the proportioning motor 46 in a direction to move the throttle valve 45 towards closed position. This will result in decreasing the fuel supply to the engine, thereby decreasing the operation of the compressor in a manner to prevent further decrease in suction pressure. Upon falling temperature, therefore, the system will act to decrease the flow of air over the cooling coil 9 and this will result in the suction pressure controller causing slowing down of the engine speed. The control system which we have disclosed will therefore act to vary the engine speed in accordance with the cooling load.

Upon continued fall in cooling load the space temperature will decrease further, this eventually resulting in partially closing of the face dampers i2 and opening of the by-pass dampers l3, thereby reducing the air flow across the cooling coil 9 to a minimum. At this time the mercury switch 212 will be tilted to closed position by the cam 210 which causes operation of the pump 42 for supplying heated fluid to the reheater l6, thereby preventing any further fall in temperature.

It will be noted that in this embodiment the proportioning motor 46 which positions the throttle valve 45 actuates also a mercury switch 215, this mercury switch corresponding to the mercury switch I02 of Figure 1. Thus whenever the throttle valve 45 is closed to such an extent as to indicate that the engine is operating at too low a speed for satisfactory'operation, the mercury switch 215 will be tilted to open position. this causing stopping of the engine. It will also be apparent that as the suction pressure rises and causes the proportioning motor 48 to open the throttle valve 45 to such an extent as to demand operation of the englne ata satisfactory speed, the mercury switch 215 will be tilted to closed position, this energizing the ignition circuit for the engine and also energizing the starting apparatus therefor, thereby placing the engine in operation. By this arrangement, therefore, the 6 speed of the engine will be varied in accordance with the refrigeration load, and when the refrigeration load fails to such an extent as to require operation of the engine at too low a speed the engine will be placed out of operation.

While we have shown and described only two forms which our invention may take, it is obvious that many other changes which are within the scope of our invention will b apparent to those skilled in the art. We therefore desire to be limited only by the scope of the appended claims and the prior art.

We claim as our invention:

1. In an air conditioning system, in combination, a cooling device through which air in a space is adapted to be passed for a conditioning action, a by-pass for flow of air around said cooling device, damper means for controlling the proportions of air passed through said cooling device and through said lay-pass, damper motor means for positioning said damper means, means including thermostatic means responsive to the temperature in said space for controlling said damper motor means, means for supplying cooling fluid to said cooling device comprising a mechanical refrigeration system including a compressor, a variable speed internal combustion engine for driving said compressor at varying speeds, a speed controller for said engine, automatic starting mechanism for said engine, said automatic starting mechanism having a control switch, a motor for actuating said speed controller and said control switch in a manner to start said engine and increase the speed of said engine as said motor moves from one position to another, a controller for controlling the position assumed by said motor, a reheating device for reheating the air, means for recovering waste heat from said internal combustion engine, means for supplying said waste heat to said reheating device, and control means for controlling the operation of said reheating device, said control means being under the control of said thermostatic means.

2. In an air conditioning system, in combination, a cooling device through which air in a space is adapted to be passed for conditioning thereof, means for supplying cooling fluid to said cooling device comprising a mechanical refrigeration system including a compressor, an internal combustion engine for driving said compressor, control means for varying the output of said internal combustion engine, motor means for adjusting said control means to vary said output, humidity responsive means for controlling said motor means in a manner to cause the engine output to be increased progressively with increasing humidity, damper means for by-passing air around said cooling device, a reheating device for reheatin said air, means for recovering waste heat from said internal combustion engine, means for supplying said waste heat to said reheating device, and sequential control means for said damper means and said reheating device, said sequential control means being arranged to first position said damper means to reduce the air flow through said cooling device and then to cause operation of said reheating device.

3. In an air conditioning system, in combination, a cooling device through which air in a space is adapted to be passed for conditioning thereof, means for supplying cooling fluid to said cooling device comprising a mechanical refrigeration system including a compressor, an internal combustion engine for driving said compressor, control means for varying the output of said internal combustion engine, motor means for adjusting said control means to vary said output, humidity responsive means for controlling said motor means in a manner to cause the engine output to be increased progressively with increasing humidity, damper means for by-passing air around said cooling device, a reheating device for reheating said air, means for recovering waste heat from said internal combustion engine, means for supplying said waste heat to said reheating detemperature.

vice, and temperature responsive sequential control means for said damper means and said reheating device, said sequential controlmeans bethen to progressively increase the operation of said reheating device upon further decrease in 4. In an air conditioning system, in combination, a cooling device through which air is adapted to be passed for conditioning thereof,-means for supplying cooling fluid to saidcooling device comprising a mechanical refrigeration system having a condenser and a compressor, an internal combustion engine for driving said compressor, a. reheating device for heating said air, means for recovering waste heat from said internal combustion engine for heating said reheating device, a controller for varying the output of said internal combustion engine, motor means for variably positioning said controller, humidity responsive means in control of said motor means for variably positioning the same to vary the output of said engine, and temperature responsive means for controlling the heating effect of said reheating device and for controllingsaid motor means independently of said humidity responsive means valve, ignition means and starting means, electrical circuits in control of the ignition means and starting means of the engine, a switch in control of said circuits, electrical means in control of the fuel valve of the engine energizable in a manner to position the fuel valve in at'least two diflerent positions whereby the speed of the to increase the output of said engine upon increase in said temperature to a predetermined high value.

5. In an air conditioning system, in combina-. I

tion, a cooling device through which air passing to a space is adapted to be passed for conditioning thereof, flow control means for controlling the flow of air through said cooling device, means for supplying coolingfluid to said cooling device comprising a mechanical refrigeration system including a compressor, an internal combustion engine for driving said compressor, control means for varying the output of said internal combustion engine, motor means for adjusting said control means to vary said output, space humidity responsive means for controlling said motor means in a manner to cause the engine output to be increased progressively with inengine may be varied when the engineis in operation and to close said switch to place the engine in operation, means utilizing the waste heat from said engine for reheating the air cooled by said coil, control means responsive to the temperatureof the air in said space, control means responsive to the relative humidity of the air in said space, and connections by which one of said control means controls said electrical means to start the engine and vary the speed thereof and the other of said control means controls said electrical means to independently start said engine and controls said reheat means.

7. In an air conditioning system, in combination, a cooling device through which air is adapted to be passed fora conditioning action thereof for conditioning a space, means for supplying cooling fluid to said cooling device comprising a mechanical refrigeration system having a compressor, means for controlling the operation of said compressor in accordance with the pressures within said refrigeration system, a reheating device for heating said air, and means responsive to the temperature and humidity of the air in the space for controlling said reheating device to maintain varying temperatures therein dependcreasing humidity, space temperature responsive means for also controlling said motor means in a manner to increase the engine output independently of said humidity responsive means when space temperature rises to a predetermined highvalue, a reheater receiving waste heat from the engine, and space temperature responsive means for controlling said now control means in a manner to decrease the flow of. air through said cooling device upon decrease in temperature and for placing said reheater in operation upon further decrease in temperature.

6. An air conditioning system for conditioning a space, comprising, in combinatioma conditioning chamber, fan means for causing-air to now through said chamber to said space, means including a direct expansion cooling coil for cooling the air flowing through said chamber, a compressor connected to said direct expansion cooling coil for withdrawing. evaporated refrigerant therefrom, an internal combustion engine fordriving said compressor a fuel ent upon the humidity.

8. In an air conditioning system for a space, a conditioning chamber for the air, duct means for delivering air from the space into said conditioning chamber, means for delivering conditioned air from said chamber to said space, means for introducing fresh air into said chamber, a cooling device in said chamber, means for supplying cooling fluid to said cooling'device including a mechanical refrigeration system'having a compressor, means for controlling said compressor in accordance with the pressures within said refrigeration system, a reheating device for heating said air, and means responsive to outside temperature and inside humidity said reheating device.

9. In an air conditioning system for a space, a conditioning chamber for theair, duct means for delivering air from the space into said conditioning chamber, means for delivering conditioned air from said chamber to said space, means for introducing fresh air into said chamber, a cooling device in said chamber, means for supplying cooling fluid to said cooling device including a mechanical refrigeration system having a compressor, means for controlling. said compressor in accordance with. the pressures within said refrigerationsystem, a reheating device for heatingsaid air, and means responsive to outside temperature, inside temperature and inside humidity for controlling said reheating device.

LEO B.

- JOHN E. HAINES.

for controlling I 

